Another newbie seeking construction advice

[GBBUDD]

The amount of money and space you'll save in block and mortar will give you literally 1/3 to 1/2 More area for the bog and extra filtration more dwell time is a bonus you should seriously consider

 

[combatwombat]

My civil engineer friend likes to joke: Anyone can design something that will stand up forever. But building materials are expensive. It takes an engineer to design something that will barely stand up forever.

 

[brokensword]

sniff; I was sorta waiting to see the bomb shelter built. Spoilsports!

 

[poconojoe]

My civil engineer friend likes to joke: Anyone can design something that will stand up forever. But building materials are expensive. It takes an engineer to design something that will barely stand up forever.

And there have been many engineering fails due to pushing the limit.
They have a whole TV series documenting that on the History channel!

I'm not discounting the knowledge or mental pressure that engineers deal with. I wouldn't want that responsibility.

 

[stavo]

I really appreciate everyone's great feedback. One thing that's not evident from this picture though is that this is a berm that I created with dirt that came out of the pond. It's not at all solid as it might have been if it had always been there naturally. When I walk up the side, I can feel some give. Once I layer small boulders around the outside, the whole thing might collapse in on itself. So the blocks would provide stability. Also, this won't have the aquablocks that Lisa mentioned (those are in my neg edge reservoir). This will only consist of the manifold at the bottom and layers of gravel above. Has anyone else built their own berm (as oppose to simply digging into higher ground above the pond) and found that it remained structurally sound just with the gravel within?

 

[addy1]

this is a berm that I created with dirt that came out of the pond.

My entire bog (27 feet) is a dirt berm, the low slope side is around 6-8 feet tall all dirt from the pond, the upper side is dirt from the pond, even the down slope side of the pond is a built up berm. Still standing 11 years later. We are on a good slope

 

[Jhn]

Yep had a berm around my bog, no issues. How do you think it is going to collapse into the bog, if the bog is filled with rock and gravel? You would need the whole area to shift somehow for that to happen, and in a flat area that you are building where is the collapse going to push stuff to.

 

[GBBUDD]

My civil engineer friend likes to joke: Anyone can design something that will stand up forever. But building materials are expensive. It takes an engineer to design something that will barely stand up forever.

After 40 years of construction i have yet to meet even one of those . i just built a small security building and its foundation while sitting on ledge had almost as much steel in it as a bridge . they isisaly get paid the more the job costs the more they make so it's wayyyyyyyyyyyyyyyyyyy over engineered

 

[GBBUDD]

And there have been many engineering fails due to pushing the limit.
They have a whole TV series documenting that on the History channel!

I'm not discounting the knowledge or mental pressure that engineers deal with. I wouldn't want that responsibility.

Ive been lucky i have never got a set of prints that were to weak . all have some sorta issues nut fortunately very rarely structurally

 

[stavo]

Well, two years later... hello again! I hope you all have continued to receive maximum enjoyment from your ponds and water gardens.

For me, this is becoming the project that never ends. But I have an excuse. We purchased a project property and have been fixing it up the last two years. It's going to go on the short-term rental market soon, and now that we're near the end on that, I'm back to focusing on the pond.

If you've followed this thread (and actually remember any of it since the last post), I was toying with the idea of having a horseshoe shaped pond with a waterfall and stream both sourcing the pond. In the interest of getting this done (which would thrill the wife to no end), I've decided to downsize the project by removing the stream, and much to the her delight that decision was cemented by purchasing the 30x30 liner - smaller than originally planned.

The new design is much simpler: roughly 8' x 8' pond with 4' depth, emptying into a negative edge reservoir containing aquablocks, the pump in a vault, and a float valve, and routing into an upflow bog above the pond which will feed the waterfall back into the pond.

One more update from me today, and I expect this will set me up for some ridicule. Much against the advice from a few of you, we proceeded to not only concrete-block in the bog, but the cistern as well - pictures to follow, especially for the person who had commented they were disappointed they wouldn't get to see the "bomb shelter." I agree that for the bog it is probably overkill, and yes, it decreased the volume of space so I'm second-guessing it. For the cistern, we felt we needed it for two reasons: The dirt underneath the edge of the adjacent flagstone patio was starting to cave into the hole we dug two years ago, and the arbutus tree's roots were also infringing into the space.

This is the cistern, with negative edge to the left. At the far end are holes for water supply, electrical, and water output.

This is the shell of the bog, with a lower edge for the weir.

And lastly, the main hole... the pond, 95% dug. I plan to extend it a little to the left so that it's more centered with the bog above.

I'll continue to post progress pics and I'm sure I'll have more questions, and as always am open to advice, critiques, or ideas on how to improve the design before it's too late.

 

[GBBUDD]

For me, this is becoming the project that never ends.

we or I have no idea what your talking about.......

i would suggest a quick skim coat of mortar in your corners rounding them so that your liner inside doesn't stretch into the hard 90 degree corners and at the floor and at the top youll want to ease the edges of the blocks/ round them so they don't cut the liner as it goes over the edge

welcome back

 

[Laaf]

Looking good!

My only suggestion is to make the weir cut out deeper than you think it needs to be.

I know it is counterintuitive to many, myself included, that water could be at a higher level/elevation at the back of the bog than near the weir. Because water with an escape route should be at the same level through out, right?

Add gravel and plants and roots and more plants and raising gravel due to roots and the water level at the back end of my bog is inches higher than by the weir due to all of the resistance and friction.

If your weir is only a few inches lower than the top edge all around, this will create risk of overflows and potentially drain your pond.

If you make the weir deeper as I am suggesting, or alternately raise the rest of the walls, if it is too low you can build it up or add resistance by stacking rocks across the weir that can be removed as the bog fills in heavily with plants and creates dams that raise the level before it hits the weir.

When my bog was being built, I made them take out a whole layer of blocks and they thought I was being silly. But, even with a whole layer out of the weir, the water has raised to the max level at the back of the bog.

My bog is long and skinny more like a stream due to the space I had to work with. So I may have a bigger rise in water level at the back than most people due to all of the extra distance for resistance and dams.

Here is a pic from my pond looking at where my bog waterfalls back into the pond. I just measured and it is 9 inches from top of the weir to top of the sides of the bog. There is a decorative cap of stone on top and the water does not go as high as the rock cap in back. But it is just below it.

At the weir, the water level is as expected, just above it. It is the back of the bog that the water level is much higher than I expected and this changes with plant density and level of rock. If the water level is getting too high for my comfort and I am afraid of overflow from the back or sides, I carve out some small valleys for water to be able to get out faster and I can lower the back of the bog water level.

I am also including the pic of how high the pond builder made the bog weir, which appears closer to what you have. This was before I had them take off the top layer of blocks. And I am very glad that I did. Here is a pic of my bog from the back with that top layer of brick removed, mid rocking. ((Even with this much lower weir the water is inches higher at the back of the bog than at the weir))

Yay to my pond builder! They had never built a bog, but they had done many multi level ponds. And they were willing to work with me and give a bog a try. If it was me, I would have run the bog waterline over the top but they wanted to hide it better by doing it this way. It has a unidirectional valve so it will not drain the bog if water is not pumping through the pipes.

 

[Laaf]

I am going through old pics from September 2022. Here is the bog newly filled with pea gravel and newly planted. You can see the plain concrete area between the top of the gravel and the bottom of the decorative rock cap. Now after almost a year of plant growth, the water level is within 1-2 inches of the decorative cap at the back of the bog.

My advice is to build the bog walls much higher than the weir than you imagine will ever overflow, and hopefully you will be correct.

The cat tails are in a pot buried in the bog since I was warned they are so invasive and hard to get out. I look forward to needing to thin the growing plants.

The grown in bog pic in my earlier post is from this month.

 

[GBBUDD]

My first bog I made my sides about 4 to 6 I ches a bove the gravel. The weir was about a foot and a half.
Two lessons I learned
1. plants grow fast.and when they do they can back up the water quickly.

2. The more they grow the more potential for trouble. The old stems started to wick water up over the edge like a straw.
Or the closed up opening back up the water.

My remake of the main bog now has 8 to 10 inch sides that do block some view but only minimaly

your setup certainly has naturalized nicely

 

[stavo]

Thank you both. Great advice and I will make modifications as you suggested.